Kidney Donation with Localized Oropharyngeal AL Amyloidosis After 6 Years of Normal Surveillance
A patient with truly localized oropharyngeal AL amyloidosis who has maintained normal bone marrow studies, 24-hour urine tests, and comprehensive labs for 6 years can be considered for kidney donation, provided rigorous evaluation confirms no systemic involvement and the patient understands the theoretical risk of future progression. 1
Critical Distinction: Localized vs. Systemic Disease
The fundamental issue is confirming that the amyloidosis remains truly localized, as systemic AL amyloidosis affects the kidneys in approximately 70% of cases and would be an absolute contraindication to donation. 2
Required Comprehensive Evaluation
Before proceeding, the following assessments must demonstrate no systemic involvement:
Hematologic screening must include serum immunofixation electrophoresis (SIFE), urine immunofixation electrophoresis (UIFE), and serum free light chain (FLC) assay with kappa/lambda ratio, as the combination of all three tests is required to identify amyloidogenic light chains with 100% sensitivity. 3
Renal function assessment should utilize cystatin C-based GFR measurements rather than creatinine-based methods, as these are more accurate in patients with potential amyloidosis and avoid overestimation of kidney function. 4
Proteinuria screening through 24-hour urine collection with protein electrophoresis is essential, as nephrotic syndrome with high-grade proteinuria is the predominant manifestation of renal AL amyloidosis. 4
Cardiac evaluation including NT-proBNP and troponin levels is necessary to exclude cardiac involvement, which would indicate systemic disease. 2
Repeat bone marrow biopsy may be warranted to confirm absence of plasma cell dyscrasia, as the amyloidogenic clone in AL amyloidosis is typically small and could evolve over time. 2
Risk Assessment Framework
Favorable Factors in This Case
Six years of stability with normal bone marrow and 24-hour urine tests suggests the disease has remained localized without progression to systemic involvement. 1
Normal laboratory surveillance including absence of proteinuria and normal renal function indicates no subclinical kidney involvement. 1
Theoretical Concerns
Risk of progression: While localized amyloidosis can remain stable, there is a theoretical risk of progression to systemic disease over time, though this appears unlikely after 6 years of stability. 1
Recurrence in transplanted organs is a concern with systemic amyloidosis but is not applicable in cases of truly localized disease. 1
Specific Monitoring Protocol
Post-donation surveillance should include:
Periodic assessment for proteinuria at regular intervals (every 6-12 months) to detect any emergence of renal involvement. 1
Serial serum FLC measurements combined with immunofixation studies to monitor for development of systemic disease. 5, 3
Annual cardiac biomarkers (NT-proBNP, troponin) to screen for cardiac amyloid deposition. 2
Kidney function monitoring using cystatin C-based eGFR, which is standard for all living kidney donors but particularly important in this context. 1, 4
Critical Caveats
The donor must be fully informed that:
While 6 years of stability is reassuring, lifetime surveillance will be necessary to detect any progression to systemic disease. 1
Any future development of proteinuria, cardiac symptoms, or other organ dysfunction requires immediate evaluation for systemic amyloidosis. 1
Standard living donor evaluation protocols must be followed with additional scrutiny for subclinical systemic involvement. 1
A common pitfall is assuming localized disease based solely on clinical presentation. The comprehensive laboratory evaluation outlined above is mandatory to exclude occult systemic involvement, as AL amyloidosis can present with vague symptoms and affect multiple organs. 6
The evaluation should be performed at a specialized center with expertise in amyloidosis, as adequate technology and expertise are required for proper workup and interpretation of results. 7